Spectral sensitization of silver halide lippmann emulsions

ABSTRACT

PHOTOGRAPHIC SILVER HALIDE EMULSIONS OF THE LIPPMANNTYPE ARE DESCRIBED WHICH COMPRISE AS A SPECTRAL SENSITIZER A MEROCYANINE DYE OF THE FORMULA:   2-(S=),3-R3,4-(O=),5-((-N(-R1)-Z-)&gt;C=CH-C(-R2)=)   THIAZOLIDINE   WHEREIN: Z REPRESENTS THE ATOMS NECESSARY TO CLOSE A PYRROLINE NUCLEUS OR A TETRAZOLE NUCLEUS, R2 REPRESENTS HYDROGEN, AN ALIPHATIC GROUP OR AN ARYL GROUP, AND EACH OF R1 AND R3 STANDS FOR AN ALIPHATIC GROUP OR AN ARYL GROUP, ONE OR R1 AND R3 COMPRISING A SULPHO GROUP, A CARBOXY GROUP, A SULPHATO GROUP, A PHOSPHONE GROUP OR A SULPHAMOYL OR SULPHONYL-CARBAMOYL GROUP. THESE DYES HAVE AN EXCELLENT SENSITIZING ACTION IN THE GREEN REGION OF THE SPECTRUM AND CAN BE USED IN HIGH CONCENTRATIONS WITHOUT LEAVING RESIDUAL STAIN IN THE EMULSION AFTER PROCESSING AND WITHOUT PRODUCING FOG.

United States Patent C) 3,705,038 SPECTRAL SENSITIZATION F SILVER HALIDE LIPPMANN EMULSIONS Herman Adelbert Philippaerts, Mortsel, Theofiel Hubert Ghys, Kontich, and Henri Depoortcr, Mortsel, Belgium, assignors to Gevaert-AGFA N.V., Mortsel, Belgium No Drawing. Filed Oct. 7, 1970, Ser. No. 78,936 Claims priority, application Great Britain, Jan. 20, 1970, 2,769/70 Int. Cl. G03c 1/22 U.S. Cl. 96-140 Claims ABSTRACT OF THE DISCLOSURE Photographic silver halide emulsions of the Lippmanntype are described which comprise as a spectral sensitizer a merocyanine dye of the formula:

wherein:

Z represents the atoms necessary to close a pyrroline nucleus or a tetrazole nucleus,

R represents hydrogen, an aliphatic group or an aryl group, and

each of R and R stands for an aliphatic group or an aryl group, one of R and R comprising a sulpho group, a carboxy group, a sulphato group, a phosphone group or a sulphamoyl or sulphonyl-carbamoyl group.

These dyes have an excellent sensitizing action in the green region of the spectrum and can be used in high concentrations without leaving residual stain in the emulsion after processing and without producing fog.

The present invention relates to the spectral sensitization of light-sensitive silver halide emulsions of the Lippmanntype.

Lippmann emulsions are of particular importance for the preparation of photographic plates used as masks in the production of micro-electronic integrated circuits. For this purpose drawings are made on highly enlarged scale of the various successive circuits necessary to produce one integrated circuit whereupon the drawings are reduced, and reproduced on a photographic plate forming thereby the mask ready for use.

Lippmann-emulsions for micro-electronic mask making should have a high resolving power in order to allow a correct reproduction of the dimensions of the images. In order to obtain emulsions with high resolving power and high sensitivity, high concentrations of spectral sensitizers are required in the emulsions. These high concentrations enhance the risk of residual stain being left in the material upon processing and the speed of the material being lowered by desensitization.

Moreover, Lippmann-emulsions for microelectronic mask-making should be orthochromatically sensitized since the spectral region of the exposure light used in the production of the microelectronic mask is situated near 545 nm. A strong orthochromatic sensitization is required so that processing of the material with fairly bright darkroom safelight illumination is possible.

Most of the known orthochromatic sensitizing dyes,

"ice

though they are satisfactory for use in ordinary photographic material, are unsuitable for use in these Lippmann-emulsions because when used in the required high concentrations they leave residual stain upon processing or give rise to fogging.

It has now been found that merocyanine dyes corresponding to the following general formula:

wherein Z stands for the atoms necessary to close a pyrroline nucleus or a tetrazole nucleus,

R stands for hydrogen, an aliphatic group including a saturated aliphatic group, an unsaturated aliphatic group and a cycloaliphatic group for example alkyl e.g. methyl and ethyl, aralkyl e.g. benzyl and cycloalkyl e.g. cyclohexyl or an aryl group such as phenyl, which groups may carry further substituents, and

each of R and R stands for an aliphatic group including a saturated aliphatic group, an unsaturated aliphatic group and a cycloaliphatic group for example C -C alkyl, allyl, benzyl, and cycloalkyl or an aryl group, which groups may carry substituents, one of R and R comprising a sulpho group in acid or salt form, a carboxy group in acid or salt form, a sulphato group in acid or salt form, a phosphono group in acid or salt form or a sulphamoyl or sulphonylcarbarnoyl group in acid or salt form for instance one of R and R being carboxylalkyl e.g. carboxymethyl, carboxyethyl, 1,2-dicarboxyethyl, carboxyaryl e.g. carboxyphenyl, carboxybenzyl, sulphoalkyl e.g. sulphoethyl, sulphopropyl, sulphopropenyl, 2-chloro-3-sulphopropyl, 2-acetoXy-3-sulphopropyl, sulphobutyl, sulphobenzyl, sulphoaryl e.g. sulphophenyl, sulphatoalkyl e.g. sulphatoethyl, sulphatopropyl and sulphatobutyl, phosphonoalkyl e.g. phosphonopropyl and phosphonobutyl, the group e.g. as described in United Kingdom patent specification 904,332 filed July 5, 1957 by Gevaert Photo-Producten N.V., wherein each of W and V represents carbonyl, sulphonyl or a single bond, at least one of W and V being sulphonyl, A represents an alkylene group e.g. a C -C alkylene group and B represents hydrogen, alkyl including substituted alkyl, amino including substituted amino, e.g. acylamino, diethylamino, or dimethylamino, with the proviso, however, that B does not represent hydrogen when V represents carbonyl or sulphonyl, the group --AWNH-V-B being exemplified by N-(methylsulphonyl)-carbamoyl-methyl, 'y-(acetylsulphamoyD- propyl, and 5-(acetylsulphamoyl)-butyl,

lend themselves perfectly for spectrally sensitizing Lippmann-emulsions, in that they have an excellent sensitizing action for Lippmann-emulsions in the green region of the spectrum with their main absorption comprised between 500 and 550 nm., that they can be used in high concentrations without giving rise to desensitization and without leaving residual stain in the photographic material after processing, and that they produce no fog.

Exemplary merocyanine dyes falling within the ambit of the above general formula and particularly suitable for the spectral sensitization of Lippmann-emulsions are listed in the following table.

, Abs. max. R1 R1 RI (nm.) c.10

01H; H CH:GOOH 484 8.4 OgHs H CH:-H1OOOH 480 7.9 11 H CH-CH:COOH 480 5.7

C O OH 4 .-d0 C2115 H CHI-CH2S 0111 482 6.3

6 d0 CzHs H 480 7. 6

C O OH 6 "d0 CzHs H 485 8. 3

S OzNa H CIHI 482 8. 5 H CaHs 478 7. 4 H CzHs 480 7. 8 H Calls 480 8. 5 CH: CH:CHsOOOH 490 5.2

C O OH I OH: CaHa 485 B. 4

14 ..do CH1) O- S OxNa CH: 01H: 495 7. 4 d CnHi 495 7. 92 CgHs 491 7. 4 C2Hs 495 6. 6 02H: 490 6. 6 CaHs 488 7. 8 C 2H5 490 7. 2 C2H5 486 7. 4

The spectral data given in the above table were measwherein:

ured in methanol, except for dye 6 where the measurement occurred in methanol-water (1:1, dye 18 where the measurement occurred in dimethylformamide and dye 20 where the measurement occurred in dimethylformamidemethanol (1:25).

The merocyanine dyes of use according to the present invention are partly known e.g. from United Kingdom patent specifications 654,683 filed Feb. 24, 1947 by Kodak 00., 1,090,626 filed Oct. 11, 1965 by Agfa AG and 1,120;- 047 filed Apr. 26, 1966 by Ilford. They can be prepared by methods well known to those skilled in the art e.g. by condensing:

(a) A cycloammonium quaternary salt corresponding to the formula:

wherein:

Z, R, and R have the same significance as above,

Q stands for a fi-arylamino group, preferably an acylated ,B-arylamino group, e.g. fi-acetanilido, or an alkoxy group, and

X- stands for an anion, or is not present when R, contains an anionic group,

with a rhodanine compound corresponding to the formula:

wherein R has the same significance as above:

(b) A cycloammonium quaternary salt corresponding to the formula:

Z and R and X have the same significance as above, and R is lower alkyl, with a rhodanine compound correspondto the formula:

. l S Hie-4T 0 ii wherein R and R have the same significance as above;

(0) Or a cycloammonium quaternary salt corresponding to the formula:

C-CH;

where Z, R X have the same significance as above, with a rhodanine compound of the formula:

Y'- R! s .Ar-N- T 0 wherein:

Y is hydrogen or acyl, Ar is aryl, and R and R have the same significane as above.

Preparation 1: Dye 4 2.8 ml. (0.02 mole) of triethylamine was added to a refluxing mixture of 3.42 g. (0.01 mole) of 1-ethyl-2-(2- anilinovinyl)-pyrrolinium iodide, 2.41 g. (0.01 mole) of 3-(2-sulphoethyl)-rhodanine, 45 ml of acetonitrile and 1.1 ml. (0.01 mole) of acetic anhydride. Refluxing was continued for 30 minutes and the dye, which crystallized upon cooling, was recrystallized from isopropanolzwater. Yield: 0.9 g. (25%). Melting point: above 260 C.

Preparation 2: Dye 11 (a) 3 (2-carboxyethyl)-5-isopropylidene-rhodanine.- 20.5 g. (0.1 mole) of 3-(2-carboxyethyl)-rhodanine, 2.8 g. of ammonium malonate and 100 ml. of acetone were refluxed for 18 hours Upon cooling, the product was filtered by suction, washed with acetone and dried. Yield: 23.7 g. (97%). Melting point: 210 C.

(b) Dye 11.2.57 g. (0.01 mole) of 1 methyl-2- methylthio-pyrrolinium iodoxide, 2.45 g. (0.01 mole) of 3 (2 carboxyethyl) 5 isopropylidene rhodanine, 30 ml. of acetonitrile and 2.8 ml. (0.02 mole) of triethylamine were refluxed for minutes.

The mixture was poured into ether and the precipitated dye was recrystallized from ethanol-water (l/l). Yield: 0.9 g. (27%). Melting point: 220 C.

Preparation 3: Dye 14 11 ml. of Z-methylthio-pyrroline, 14 g. of propylene sulphate and 10 ml. of acetonitrile were heated to 70-75 C. on a water-bath until an exothermic reaction started. Heating was interrupted until the reaction slackened and then continued for 20 minutes. The mixture was cooled to ambient temperature whereupon 60 ml. of acetonitrile, 60 ml. of ethanol and 15 g. of 3 ethyl 5 isopropylidene rhodanine were added. Then, 28 ml. of triethylamine were added dropwise with stirring in the course of 1 hour. Stirring was continued for 8 hours whereupon the mixture was left standing overnight, poured into 200 ml. of water and extracted twice with ether. The aqueous layer was saturated with sodium chloride and the dye which crystallized was purified by recrystallization from ethanol-water. Yield: 1.5 g. Melting point: 250 C. (decomposition).

Preparation 4: Dye 18 7.5 g. (0.02 mole) of 1-phenyl-5-methyl-4-(methylcarbarnoylmethyl)tetrazolium bromide, 6.12 g. (0.02 mole) of 5 acetanilidomethylenerhodanine, 50 ml. of pyridine and 5.6 ml. (0.04 mole) of triethylamine were refiuxed for 15 minutes. After dilution with water the precipitated dye was recrystallized from isopropanol. Yield: 2.8 g. (30%).

Preparation 5: Dye 20 This dye was prepared in an analogous way as dye 18 starting from 1 phenyl-5-methyl-4-(4-sulpharnylbutyl) tetrazolium bromide. Yield: 34%.

Preparation 6: Dye 21 This dye was prepared from 0.6 g. of the dye of preparation 5 by recrystallization from acetic anhydride. Yield: 0.3 g. Melting point: 245 C. (decomposition).

In accordance with the present invention, photographic materials are provided comprising at least one lightsensitive silver halide emulsion of the Lippman-type con taining at least one sensitizing dye corresponding to the above general formula.

The ratio of hydrophilic colloid binder to silver halide in the Lippmann emulsions according to the present invention is preferably comprised between 1:5 and 15:1. The thickness of the emulsion layer of a photographic material according to the present invention is generally comprised between about 3 microns and 8 microns and the average grain size of the silver halide grains is at most 0.1 micron, generally less than 0.08 micron.

The liydrophilic colloid used as the vehicle for the silver halide may be any of the common hydrophilic colloids employed in photographic light-sensitive emul- 6 sions, for example gelatin, agar-agar, albumine, zein, casein, collodion, alginic acid, water soluble cellulose derivatives such as carboxymethylcellulose, polyvinyl alcohol, poly-N-vinyl pyrrolidone or other hydrophilic synthetic or natural resins or polymeric compounds, gelatin being however favoured. If desired, compatible mixtures of two or more colloids may be employed for dispersing the silver halide.

Various silver salts may be used as the light-sensitive salt such as silver chloride, silver bromide, silver iodide or mixed silver halides such as silver chlorobromide, silver bromoiodide and silver chlorobromoiodide. Silver bromide emulsions having an average grain size of at most 0.1 micron and an iodide content comprised between 0 and 8 mole percent are favoured.

Sensitization of Lippmann emulsions by means of the sensitizing dyes according to the above general formula occurs by incorporating the acid dyes or their salts into the said emulsions by one of the methods customarily employed in the art. In practice, it is convenient to dissolve the dyes in water, methyl alcohol, ethyl alcohol or a mixture of one of these alcohols with water and to disperse the solution formed into the washed, finished emulsion so that the dye is uniformly distributed throughout the emulsion. It is apparent of course that the dyes can be incorporated by other methods and at any stage of emulsion preparation.

The concentration in the emulsion of the sensitizing dyes corresponding to the above general formula can vary between wide limits. Up to 1000 mg. and preparably from 300 mg. to 700 mg. of dye are used per mole of silver halide. The most suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customary in the art of emulsion making.

The dyes are preferably incorporated into photographic emulsions the general sensitivity of which has been increased by chemical ripening. These emulsions may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur containing compounds such as allyl isothiocyanate, allyl thiourea, sodium thiosulphate, potassium selenocyanide, etc. The emulsions may also be sensitized by means of reducing sensitizers such as tin compounds, imino-aminomethane sulphinic acids and the derivatives thereof, cadmium salts, and the salts of noble metals such as gold, platinum, palladium, iridium, ruthenium and rhodium.

Lippmann emulsions spectrally sensitized in accordance with the present invention may also comprise light-absorbing dyes to reduce scattering and reflection of light within the photographic material, said dyes being chosen so as to absorb light of the wavelength to which the material is exposed and may be any of the light-absorbing or filter dyes customarily employed in common photographic light-sensitive materials including oxonol dyes, arylidene dyes, styryl dyes, triarylmethane dyes, azo dyes, etc. Further details as to the use of these light-absorbing dyes in Lippmann-emulsions can be found in United Kingdom patent specification 1,139,062 filed Jan. 1, 1965 by Kodak Co. and in Belgian patent specification 742,954 filed Dec. 11, 1969 by Gevaert-Agfa N .V.

The emulsions may further comprise compounds restraining the growth of the silver halide crystals during precipitation so that emulsions can be prepared with an average silver halide grain-size markedly smaller than in the absence of said compounds. In this connection there can be referred to Belgian. patent specification 710,602 filed Feb. 23, 1967 by Kodak Co. and to United Kingdom patent applications 53,025/69 filed Oct. 19', 1969 and 54,539/ 69 filed Nov. 6, 1969 both by Gevaert-Agfa N.V.

In preparing the photographic emulsions according to the invention the usual and suitable addenda such as antifoggants, stabilizers, development accelerators, plasticizers, wetting agents and hardeners are also incorporated into the emulsion in a known manner.

Suitable hardening agents are amongst others formaldehyde, halogen-substituted aldehydes comprising a carboxyl group such as mucobromic acid, diketones, dialdehydes, etc.

Compounds suitable for sensitizing the emulsions by development acceleration are e.g. compounds of the polyoxyalkylene type such as alkylene oxide condensation products as described amongst others in US. patent specifications 2,531,832 of William Alexander Stanton, issued Nov. 28, 1950 and 2,533,990 of Ralph Kingsley Blake, issued Dec. 12, 1950, in United Kingdom patent specifications 920,637 filed May 7, 1959, 940,051 filed Nov. 1, 1961, 945,340 filed Oct. 23, 1961 all three by Gevaert Photo-Producten N.V. and 991,608 filed June 14, 1961 by Kodak Co., and in Belgian patent specification 648,710 filed June 2, 1964 by Gevaert Photo-Producten N.V. as well as onium derivatives of amino-N-oxides as described in United Kingdom patent specification 1,121,696 filed Oct. 7, 1965 by Gevaert-Agfa N.V.

Among the stabilizers customarily employed in emulsions may be mentioned mercury compounds such as the mercury compounds described in Belgian patent specifications 524,121 filed Nov. 7, 1953 by Kodak Co., 677,3 37 filed Mar. 4, 1966 and 707,386 filed Dec. 1, 1967 both by Gevaert-Agfa N.V., US. patent specification 3,179,520 of Yoshio Miura, Akira Kumai and Yosuke Nakajima, issued Apr. 20, 196 5, heterocyclic nitrogen containing thioxo compounds such as those described in the German patent specification 1,151,731 filed Mar. 8, 1962 by Agfa AG, benzothiazoline 2 thione and 1-phenyl-2-tetrazo1ine-5- thione and compounds of the hydroxytriazolopyrimidine type such as -methyl-7-hydroxy-s-triazolo[1,5-a]pyrimi dine.

The Lippmann emulsions sensitized in accordance with the present invention may be coated on a wide variety of photographic emulsion supports. Typical supports include cellulose ester film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film and related films of resinous materials as well as paper and glass. In the manufacture of high-resolution plate materials for the preparation of masks for use in the electronic industry glass supports are most advantageously used in view of their high dimensional stability.

In order to promote adhesion of the emulsion to glass supports in the preparation of high resolution plate materials the silicon compounds described in Belgian patent specification 741,820 filed Nov. 18, 1969 by Gevaert-Agfa N.V. can be incorporated into the emulsion.

The following example illustrates the use of the sensitizing dyes according to the above general formula for the spectral sensitization of Lippmann-emulsions in comparison to other merocyanine dyes of closely related structure.

EXAMPLE A silver bromide emulsion comprising 72 g. of silver bromide and 93 g. of gelatin was prepared by simultaneous addition of a silver nitrate solution and a potassium bromide solution to a 3% aqueous solution of gelatin. The conditions of precipitation were adjusted so that a Lippman emulsion with an average grain size of 007g was obtained. Details as to the preparation of Lippmann emulsions can be found amongst others in P. Glaf-kids Photographic Chemistry, vol. 1, 1958, Fountain Press, London. The emulsion was divided into several aliquot portions and to each portion one of the sensitizers listed in the table below were added in an amount of 0.94 millimole per mole of silver halide.

The emulsions were then coated on glass plates and dried so as to obtain an emulsion layer thickness of 5 microns.

The materials thus obtained were exposed in a sensitometer once without filter (general sensitivity) and once through a yellow filter (spectral sensitivity) the transmission of which for light of a wavelength shorter than 460 nm. is less than 0.1% and for light of a wavelength longer than 520 run. is more than 90%.

The sensitometric results obtained as well as the percentage residual staining measured after processing at the A of the dyestufi concerned are listed in. the table below.

Exposure without filter Exposure through filter Relative Relative 8.... ass :32:5 iant Dye max. Fog (log Et) Fog (log Et) staining None. 420 0. 05 1. 88 0. 05 0 0,11 540 0. 05 0. 0. 06 0. 78 16 l. s 1120 C=CHCH=C C=S Hz( JH1 0=( JN lzHs s 540 0. 04 1. 12 0. 05 1.10 14 H:G C=CHCH=C C=S H2CN O=CN (CHz)aO S OaNa 12115 S e S 540 0. 12 0. 97 0.10 0. 93 15 H:C C=CHCH=C C=S HAL-l. o= l lHs HaCHzCOOH 0:115 540 0. 08 0. 91 0. 08 0. 17 l. OC=GH--CH==C C=S CiHi N O=CN .N-CzHl Hfl O S 05H CH: CIHI 3Z8 311:: 33.? 333% i 3332 iii '3 Dye 17 540 0. 04 l. 09 0. O4 1. 10 1. 5 Dye 18-- 550 0. 06 1. 22 0. 05 1. 18 1. 6

l A decrease by 0.3 of the log Et values, which are measured at density 1 above log, means a doubling of the speed.

The preceding results show that the spectral sensitizers corresponding to the above general formula leave less strain in Lippmann emulsions than closely related merocyanine dyes and in some instances also produce less fog.

We claim:

1. Photographic silver halide emulsion of the Lipprnann-type comprising a hydrophilic colloid as binder for the silver halide and a spectrally sensitizing amount of a merocyanine dye corresponding to the formula:

wherein:

Z stands for the atoms necessary to close a pyrroline nucleus or a tetrazole nucleus,

R stands for hydrogen, an aliphatic group or an aryl group, and each of R and R stands for an aliphatic group or an aryl group, one of R and R comprising a sulpho group in acid or salt form, a carboxy group in acid or salt form, a sulphato group in acid or salt form, a phosphono group in acid or salt form or a sulphamoyl or sulphonylcarbamoyl group in acid or salt form.

2. Photographic emulsion according to claim 1, wherein the sensitizer is present in an amount up to 1000 mg. per mole of silver halide.

3. Photographic emulsion according to claim 1, wherein the light-sensitive silver halide is silver bromoiodide, comprising at most 8 mole percent of silver iodide and having an average grain size of at most 0.08p-

4. Photographic emulsion according to claim 1, where in the ratio of hydrophilic colloid binder to silver halide is comprised between 1:5 and 15:1.

5. Photographic light-sensitive material comprising a support and a silver halide emulsion layer of the Lippmann type wherein said emulsion layer comprises a dye as defined in claim 1.

6. Photographic light-sensitive material according to claim 5, wherein the emulsion layer has a thickness comprised between 3 and 8 microns.

10 7. Photographic light-sensitive material according to claim 5, wherein the support is a glass plate.

8. The photographic emulsion according to claim 4 wherein the is pyrroline, R is C H R is H, and R is 9. The photographic emulsion according to claim 4 wherein the iS pyrroline, R1 iS (CH SO Ca R2 is C2H5, and R3 is 021-15.

10. The photographic emulsion according to claim 4 wherein the is phenyltetrazole, R is CH CO-NHSO CH R2 is H, and R3 is C2H5.

References Cited UNITED STATES PATENTS J. TRAV-IS BROWN, Primary Examiner US. Cl. X.R. 96-362 UNITED STATES PATENT OFFICE CERTIFICATE OF CQRRECTION Patent No. 3, 705, 038 Dated December 5, 1972 Inventor(s) Herman Adelbert PHILIPPAERTS ET AL It is certified that error appears in the above- -identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, in the table, column headed R Dye 2, "CH H COOH" should read CH -CH COOH Column 3, in the table, column headed R Dye 11, "CH CH COOH" should read CH CH COOH Column 3, in the table, column'headedc-j. 10- Dye 16, "7.4" should read 6. 6 Column 3, in the table, column headed. 10 Dye 18, "6. 6" should read 7.4 Column 3, line 33, "(1:1, should read (1:1), Column 3, lines 46-54, the formula should appear as follows:

Column 4, line 52, "where" should read wherein Column 5, line 14, after "hours" insert Column 5, lines 44 and 45, "1-phenyl-5- methyl-4-(methybcarbamoylmethyl) tetrazolium bromide, should read 1phenyl-5-methyl-4(methylsulphonyl-carbamoylmethyl)tetrazolium bromide, Column 8, in the table, column headed Dye, the fourth formula should appear as follows:

FORM PC4050 (169) USCOMM DC 00310 P69 .5. GOVERNMENT PRINTING OFFICE 1 '85 -3i6'334,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 0 038 Dated December 5, 1972 Inventor) Herman Adelb ert PHILIPPAERTS ET AL Page 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Signeq and sealed this 16th day of July 1974.

(SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Commissioner of Patents Attesting Officer USCOMM-DC 60376-P69 u.s. GOVERNMENT PRINTING OFFICE lacs o-aea-su.

F ORM PO-I 050 (1 0-69) 

